We are interested in the structures and functions of carbohydrate components of cell membranes. Our systems include normal and transformed cells, and murine cell synthesizing free and membrane-bound immunoglobulin. The transformants include malignant and non-malignant cells. The major cell surface change which gives the best correlation with tumorigenicity can be detected by two-dimensional electrophoresis of glycoproteins or Sephadex chromatography of glycopeptides. We have isolated a cell glycoprotein of 100,000 D which appears to be a cell membrane antigen involved in tumor regression. IgM producing lines include fetal hybridomas producing mu chains only, B cell tumors producing membrane IgM, and myelomas and hybridomas producing soluble IgM. We are also initiating studies in lines producing IgG and IgA. Our studies include detailed chemical characterization of the structures of oligosaccharides at each glycosylation site on the various forms of IgM. We are also initiating studies on the biosynthesis of complex polysaccharides, and in particular how the subcellular systems can determine various carbohydrate structures on the same glycoprotein.